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  1. #1
    Join Date
    Nov 2014
    Pensacola, Florida
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    Campus Primary/Secondary Chilled Water System Low Delta T Syndrome Solved

    Campus Constant Flow Primary/Variable Flow Secondary Chilled Water System Problems

    • Chillers will only load to 70%.
    • Unable to utilize 100% of installed chiller capacity.
    • Chilled water distribution temperature not equal to or less than design of 42 Degrees F when secondary chilled water flow exceeds primary chilled water flow
    • Chillers are manually added and subtracted
    • Over pumping in decoupler piping (Wasted Pump Energy)

    Solution To Problem

    See ASHRAE Journal October 2104 Article Titled "Simplified Chiller Sequencing."

    The article presents an approah that was implemented for a campus chilled water system with four 1200 ton centrifugal chillers and solved the problems indicated for the chilled water system.

    The solution required:

    • Installation of Four Primary Pumps with Variable Frequency Drives (VFD)
    • Installation of Four Temperature Sensors
    • Removel of check valve in decoupler piping

    Mixed temperature based calculations were developed and used to control primary pump VFD speed and sequencing control for chillers.

    Results of implemented solution:

    • Chillers could be loaded to 100% if required
    • Chillers are added and subtracted automatically
    • Secondary distribbution temperature is controlled to less than design
    • Decoupler flow minimized
    • Primary chilled water flow equals secondary chilled water flow.

  2. #2
    Join Date
    Jun 2003
    in a tree looking in your window
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    I've seen that same problem many of times over, probably should have tried calibrating the kaneuter valve first, would have been a lot cheaper.
    If you dont stand behind our troops, please feel stand in front of them.

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